Depending on the application for which they are implanted in a patient, implantable medical devices (IMDs) may include a variety of electrical and/or mechanical components. In many cases, an IMD includes a rigid housing that houses all of its components, which are generally fragile, to protect the components from forces to which they would otherwise be exposed when implanted within the human body. In order to avoid potentially harmful interactions between the components and bodily fluids, e.g., corrosion, IMD housings are typically hermetically sealed. Many IMD housings are fabricated from titanium because of its desirable rigidity and biocompatibility.
The size and shape of an IMD housing is dependent on the sizes and shapes of the components of the IMD. Large components common to most IMDs include a battery and a circuit board that carries digital circuits, e.g., integrated circuit chips and/or a microprocessor, and analog circuit components. Attempts have been made to reduce the size of the IMD housing by reducing the size of these components, changing the shape of these components, and organizing these components within the IMD housing to avoid empty space within the housing.
Recently, modular IMDs that place components of the IMD in separate modules have been proposed. For example, a modular IMD may include a battery housed in a first module, digital and/or analog circuitry housed in a second module, and a telemetry coil. A common encapsulation member formed of silicone, polyurethane, or another biocompatible polymer may at least partially encapsulate the modules of the modular IMD. One or more hermetic interconnects, which may include a metallic covering over one or more conductors, may electrically interconnect the modules.